1. Field of the Invention
The present invention relates to a purification of an aqueous solution of potassium chloride by removing an anticaking reagent and a flotation reagent contained in potassium chloride by incorporating an oxidizing agent in the process for dissolving and purifying potassium chloride to produce potassium hydroxide by an electrolysis in an electrolytic cell using a cation exchange membrane.
2. Description of the Prior Art
Mercury process has been well known to produce potassium hydroxide. It has been also known to produce potassium hydroxide by a cation exchange membrane process which has been recently developed. In the mercury process, there is no trouble for electrolytic characteristics even though an anticaking reagent is dissolved in an aqueous solution of potassium chloride. Therefore, it has not been worked to remove said anticaking reagent in the production of potassium hydroxide by the mercury process.
In usual, the anticaking reagent such as higher alkylamines, for example, octadecylamine is incorporated at a concentration of several hundreds ppm so as to prevent the caking of potassium chloride in an industrial grade potassium chloride. The flotation reagent such as paraffin which is incorporated for a flotation of potash ore is usually remained at a concentration of several hundreds ppm. The compositions and properties of the anticaking reagent and the flotation reagent are not clearly disclosed. It has been known that the anticaking reagent is usually insoluble in the acidic condition of the aqueous solution of potassium chloride to be a suspension in the aqueous solution of potassium chloride, however, the anticaking reagent is usually dissolved in the alkaline condition of the aqueous solution of potassium chloride. Therefore, the anticaking reagent can be removed by filtering the aqueous solution of potassium chloride in the acidic condition. This process has not been practically employed because it has not been economical in view of substrates of filtering equipments and filtration property. On the other hand, any behavior of the flotation reagent in the electrolysis has not been known.